1. Field of the Invention
The present invention relates to a fluid compressor and, more particularly, to a fluid compressor for compressing a refrigerant gas in a refrigeration cycle, for example.
2. Description of the Related Art
Various conventional compressors such as a reciprocating compressor and a rotary compressor are known to those skilled in the art. In these conventional compressors, the structure of both the compression section and drive unit, such as a crankshaft for transmitting rotational force to the compression section, are complex, and a large number of components are required. In addition, in order to improve compression efficiency in a conventional compressor, a check valve must be arranged on its delivery side. However, the pressure difference between the inlet and outlet sides of the check valve is large, and gas tends to leak from the check valve, degrading the compression efficiency. In order to solve this problem, high dimensional precision of the constituting components and high assembly precision must be maintained, thus resulting in high costs.
A crew pump is disclosed in U.S. Pat. No. 2,401,189. In this pump, a columnar rotary member is fitted in a sleeve, and a spiral groove is formed on the surface of the rotary member, into which a spiral blade is slidably fitted. Upon rotation of the rotary member, a fluid, sealed between the adjacent turns of the blade in the space between the outer surface of the rotary member and the inner surface of the sleeve, is transported from one end of the sleeve to the other.
The screw pump can transport the fluid but does not have a function for compressing the fluid. In order to seal the transported fluid, the outer surface of the blade must always be in contact with the inner surface of the sleeve. During rotation of the rotary member, however, the blade itself is deformed in the groove, and it cannot slide easily and smoothly in the groove, and for this reason, it is difficult to keep the outer surface of the blade in slidable contact with the inner surface of the sleeve, therefore it is difficult to satisfactorily seal the fluid. As a result, the compression operation cannot be satisfactorily performed by the structure of the screw pump.